Composites (and everything else) are identical between platforms - ArchiCAD file formats are identical whether PC or Mac.
I'm guessing that you have an issue with your view options: core only, finish, entire structure and that somehow one of those gyp layers is set to be a 'finish' perhaps, but you have finishes turned off.
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB